Jan Mertl (born 3 January 1982) is a Czech former tennis player who competed mainly on the ITF Futures Tour and ATP Challenger Tour. On 23 July 2007, he reached his highest ATP singles ranking of 163.^[1]

Mertl made his ATP main draw debut at 2016 Swiss Open Gstaad, defeating Yann Marti to score his first ATP-level win.

Mertl is the coach of Czech WTA player Markéta Vondroušová.^[2]

Result	No.	Date (Final)	Tournament	Surface	Opponent	Score
Loss	1.	18 March 2007	Sarajevo, Bosnia and Herzegovina	Hard (i)	Ernests Gulbis	6–4, 4–6, 6–7(2–7)
Loss	2.	18 March 2012	Sarajevo, Bosnia and Herzegovina	Hard (i)	Jan Hernych	3–6, 6–3, 6–7(5–7)
Loss	3.	24 March 2012	Bath, Great Britain	Hard	Dustin Brown	6–7(1–7), 4–6

Result	No.	Date	Tournament	Surface	Partner	Opponents in the final	Score
Loss	1.	4 September 2005	Kyiv, Ukraine	Clay	Lukáš Dlouhý	Diego Junqueira Martín Vassallo Argüello	4–6, 2–6
Loss	2.	9 July 2006	Pozoblanco, Spain	Hard	Ivo Klec	Justin Gimelstob Kevin Kim	3–6, 5–7
Loss	3.	16 July 2006	Poznań, Poland	Clay	Vasilis Mazarakis	Tomasz Bednarek Michał Przysiężny	3–6, 6–3, [8–10]
Loss	4.	4 March 2007	Wolfsburg, Germany	Carpet (i)	Joshua Goodall	Alexander Peya Lars Uebel	4–6, 4–6
Loss	5.	18 March 2007	Sarajevo, Bosnia and Herzegovina	Hard (i)	Lukáš Rosol	Ernests Gulbis Deniss Pavlovs	4–6, 3–6
Loss	6.	3 June 2007	Busan, South Korea	Hard	Nathan Healey	Sergei Bubka John Paul Fruttero	6–4, 6–7(5–7), [6–10]
Loss	7.	6 January 2008	Nouméa, France	Hard	Martin Slanar	Flavio Cipolla Simone Vagnozzi	4–6, 4–6
Win	8.	7 February 2010	Kazan, Russia	Hard (i)	Yuri Schukin	Tobias Kamke Julian Reister	6–2, 6–4
Loss	9.	17 September 2011	Sarajevo, Bosnia and Herzegovina	Clay	Matwé Middelkoop	Marco Crugnola Rubén Ramírez Hidalgo	6–7(3–7), 6–3, [8–10]

• Jan Mertl at the Association of Tennis Professionals
• Jan Mertl at the International Tennis Federation